The present invention pertains to equipment used in processing photosensitive material, and more particularly to an autoloader for feeding cassettes and/or pallets containing cassettes to and receiving them from a computed radiographic reader.
It is convenient to handle storage phosphorous film/plates within cassettes that protect the film from extraneous light and damage. Storage phosphorous film is read by photoelectrically detecting an image formed by scanning with stimulating radiation. An example of such a scanner/reader is disclosed in U.S. Pat. No. 4,789,782 to O'Hara. It is desirable to retain the x-ray film within a cassette except during actual processing. Such a cassette is disclosed in U.S. patent application Ser. No. 800,799, filed Nov. 27, 1991, entitled "X-ray Cassette Having Removable Photographic Element" by Jeffrey C. Robertson, which is incorporated herein by reference. A hook extractor can be used with the x-ray cassette to remove the photographic element for scanning in the x-ray reader. It is desirable to provide an apparatus to automate the presentation of such x-ray cassettes or similar cassettes to such an extractor so that a number of x-ray cassettes could be processed in succession without attention from an operator. It is also desirable that such an apparatus be able to accurately position x-ray cassettes and/or pallets containing cassettes sequentially to simplify removal and reinsertion of the photographic elements and that the presentation apparatus be separate from the x-ray reader to permit interchange of units and reduce repair time. An example of a suitable device for presenting cassettes is disclosed in copending application U.S. Ser. No. 902,214 filed Jun. 22, 1992, entitled "X-ray Cassette Positioner" of John C. Boutet et al which is also hereby incorporated by reference. In this reference there is disclosed a positioner/autoloader for use with a plurality of x-ray cassettes and/or pallets containing cassettes which comprise first and second cog belts spaced apart so as to provide a plurality of cassette retaining sites one of which defines a cassette read site for presenting of the cassette to the reader. The belts are driven such that the cassettes are each individually positioned at the read site for removal of the photosensitive film therein for reading by the reader after which it is returned to the cassette. The positioner allows a plurality of individual cassettes to be placed thereon for automatic supplying to the reader thus freeing the operator to accomplish other duties. It is important that the mechanism be designed to operate in such a manner so as to minimize any transfer of vibrations from the autoloader to the reader which can adversely affect the reader reading the information stored on the photo stimulable phosphorous film. Typically the autoloader will be loaded or unloaded during scanning of the photostimulable phosphorous film in the adjacent reader. The cassettes are manually loaded and unloaded from the cassette loading and unloading sites. Generally the operator will be loading or unloading a plurality of cassettes. During this procedure the operator must align the sides of the cassettes with axially spaced shelves. Thus, there is the possibility that the cassette will be banged against the sides of the autoloader adjacent the portal which could cause objectionable vibrations to be transmitted to the reader. Since the shelves forming the cassette retaining sites are spaced apart, the operator must rely on his or her ability to visually align the sides of the cassette with the appropriate opposed aligned shelves. If the cassette is not properly inserted into the cassette site, the cassette could be placed at an angle between non aligned shelves which would result in the autoloader stopping when the autoloader senses the misalignment.
In accordance with the present invention there is provided means for minimizing transfer of vibrations to the reader which can adversely affect the reading of the photographic element and means for assisting the operator to quickly and easily load cassettes between properly aligned shelves of the cassette retaining sites.